Field of the Invention
The present invention relates to a thin film transistor, a thin film transistor array panel, and a manufacturing method thereof.
Description of the Related Art
A thin film transistor (TFT) has been used in various electronic devices such as a flat panel display. For example, a thin film transistor has been used as a switching element or a driving element for a flat panel display such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, and an electrophoretic display.
Typically, a thin film transistor includes a gate electrode connected to a gate line transmitting a scanning signal, a source electrode connected to a data line transmitting a signal applied to a pixel electrode, a drain electrode facing the source electrode, and a semiconductor electrically connected to the source electrode and the drain electrode.
For higher TFT performance, fabricating transistor from thin film of a semiconductor is an important factor in determining characteristics of the thin film transistor. The semiconductor typically includes silicon (Si). The silicon can be divided into amorphous silicon and polysilicon according to a crystallization type, wherein the amorphous silicon has a simple manufacturing process, but has low charge mobility such that there is a limit in manufacturing a high performance thin film transistor using the amorphous silicon, while the polysilicon has high charge mobility, but additional, complicated processes of crystallizing the polysilicon may be required, thereby increasing the manufacturing time and cost.
To compensate weakness and benefit for the amorphous silicon and the polysilicon, various approaches have been tried for making a thin film transistor using an oxide semiconductor having higher electron mobility than the amorphous silicon, a high on/off ratio, and high uniformity, but a lower cost than the polysilicon.
However, if parasitic capacitance is generated between the gate electrode and the source electrode or the drain electrode of the thin film transistor, a characteristic of the thin film transistor as the switching element may be deteriorated despite the above various approaches.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.